Microsized nanostructured silicon-carbon composite is a promising anode material for high energy Li-ion batteries. However, large-scale synthesis of high-performance nano-Si materials at a low cost still remains a significant challenge. We report a scalable low cost method to synthesize Al/Na-doped and defect-abundant Si nanorods that have excellent electrochemical performance with high first-cycle Coulombic efficiency (90%). The unique Si nanorods are synthesized by acid etching the refined and rapidly solidified eutectic Al-Si ingot. To maintain the high electronic conductivity, a thin layer of carbon is then coated on the Si nanorods by carbonization of self-polymerized polydopamine (PDA) at 800 °C. The carbon coated Si nanorods (Si@C) electrode at 0.9 mg cm(-2) loading (corresponding to area-specific-capacity of ∼2.0 mAh cm(-2)) exhibits a reversible capacity of ∼2200 mAh g(-1) at 100 mA g(-1) current, and maintains ∼700 mAh g(-1) over 1000 cycles at 1000 mA g(-1) with a capacity decay rate of 0.02% per cycle. High Coulombic efficiencies of 87% in the first cycle and ∼99.7% after 5 cycles are achieved due to the formation of an artificial Al2O3 solid electrolyte interphase (SEI) on the Si surface, and the low surface area (31 m(2) g(-1)), which has never been reported before for nano-Si anodes. The excellent electrochemical performance results from the massive defects (twins, stacking faults, dislocations) and Al/Na doping in Si nanorods induced by rapid solidification and Na salt modifications; this greatly enhances the robustness of Si from the volume changes and alleviates the mechanical stress/strain of the Si nanorods during the lithium insertion/extraction process. Introducing massive defects and Al/Na doping in eutectic Si nanorods for Li-ion battery anodes is unexplored territory. We venture this uncharted territory to commercialize this nanostructured Si anode for the next generation of Li-ion batteries.

Nano-hydroxyapatite (HA) was directly synthesized on a silk fibroin (SF) template using the property of SF being soluble in a concentrated CaCl(2) solution as a HA source of calcium at pH 7.4 and room temperature. The microstructure and bonding state were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TG) and transmission electron microscopy (TEM). The results indicated that the HA crystals were poorly crystallized with a rod-like shape of 20-60 nm length and 10-20 nm diameter. Strong molecular interactions and chemical bonds might be present between SF and HA. There were other nucleation sites such as carbonyl (-C-O) and amine (-N-H-) groups on SF molecules besides the carboxyl (-COOH) and hydroxyl (-OH) groups previously reported. During the formation of HA, the coordination action between specific functional groups on SF and calcium ions (Ca(2+)) played an important role. The crystallinity of HA was improved and had an orientation growth along (0 0 2) at the presence of SF, resulting in a structure similar to natural bone. It was concluded that SF could regulate the structure and morphology of HA effectively.

Sulfonated poly(ether sulfone)/poly(vinylidene fluoride) (SPES/PVDF) blends are prepared and employed as the separator for vanadium redox flow battery (VRB) to evaluate the vanadium ions permeability and cell performance. The SPES/PVDF membranes exhibit dramatically vanadium ions permeability and cell performance compared with pristine SPES and Nafion115 membrane. The vanadium ion permeability of SPES/PVDF membrane is 1 order of magnitude lower than that of Nafion115 membrane. The low-cost composite membrane exhibits a better performance than Nafion115 membrane at the same operating condition. VRB single cell with SPES/PVDF membrane shows significantly lower capacity loss, higher coulombic efficiency (>98%) and higher energy efficiency (>84%) than that with Nafion115 membrane. In the self-discharge test, S0.7P0.3 membrane shows twice longer duration in the open circuit decay than that with Nafion115 membrane. With all the good properties and low cost, the SPES/PVDF membrane is expected to have excellent commercial prospects as an ion exchange membrane for VRB systems.

B doping plays an important role in improving the conductivity and electrochemical properties of Si anodes for Li-ion batteries. Herein, we developed a facile and massive production strategy to fabricate C-coated B-doped Si (B-Si@C) nanorod anodes using casting intermediate alloys of Al-Si and Al-B and dealloying followed by C coating. The B-Si@C nanorod anodes demonstrate a high specific capacity of 560 mAg-1, with a high initial coulombic efficiency of 90.6% and substantial cycling stability. Notably, the melting cast approach is facile, simple, and applicable to doping treatments, opening new possibilities for the development of low-cost, environmentally benign, and high-performance Li-ion batteries.

Used Al-13wt%Si alloy was as raw material, the influence mechanism of Al-Sr, Al-P and Al-RE ternary compound modifier was studied by casting technology. The effects of P, Sr and RE modification on Al-13wt% Si were studied by metallographic microscope, scanning electron microscope and X-ray. The effects of the addition order and amount of modifier on the microstructure of Al-13wt% Si were investigated The results show that compared with a single modifier, P + RE + Sr ternary composite modifier has more obvious modification effect on eutectic silicon in Al-13%Si alloy: the microstructure of different morphology can be obtained by using different amount and order of adding modifier. When the amount and order of modifier are 0.5wt%Sr, 0.7wt%P, 1.5wt%RE,the eutectic silicon with small size and uniform distribution can be obtained. Eutectic silicon consists of 70 μm, the slender lamella is refined to 5 μm.